Study on heat integration of supercritical coal-fired power plant with post-combustion CO₂ capture process through process simulation

Study on heat integration of supercritical coal-fired power plant

with post-combustion CO

capture process through process

2

simulation

4

Xiaoyan Liu

, Jian Chen

, Xiaobo Luo

, Meihong Wang

,

Hui Meng

a

State Key Laboratory of Chemical Engineering, Tsinghua University, Beijing 100084, China 6

b

Process and Energy Systems Engineering Group, School of Engineering, University of Hull, HU6 7

7RX, UK 8

*Corresponding author 1. Tel: +86 10 62798627; Fax: +86 10 62770304; Email: [email protected]

9

*Corresponding author 2. Tel: +44 1482 466688; Fax: +44 1482 466664; Email: [email protected]

10 11

Abstract 12

Coal-fired power plant (CFPP) is one of the main sources of anthropogenic CO2 emissions. Capturing CO2 13

from CFPP by post-combustion process plays an important role to mitigate CO2 emissions. However, a 14

significant thermal efficiency drop was observed when integrating CFPP with post-combustion carbon

15

capture (PCC) process due to the steam extraction for capture solvent regeneration. Thus research efforts

16

are required to decrease this energy penalty. In this study, a steady state model for 600 MWe supercritical 17

CFPP was developed as a reference case with a low heating value (LHV) based efficiency of 41.6%. A

18

steady state model for MEA-based PCC process was also developed and scaled up to match the capacity of

19

the CFPP. CO2 compression process was simulated to give an accurate prediction of its electricity 20

consumption and cooling requirement. Different integration cases were set up according to different

21

positions of steam extraction from the CFPP. The results show that the efficiency penalty is 12.29% and

22

14.9% when steam was extracted at 3.64 bar and at 9.1 bar respectively. Obvious improvements were

23

achieved by utilizing waste heat from CO2 capture and compression process, taking part of low pressure 24

cylinders out of service, and adding an auxiliary turbine to decompress the extracted steam. The efficiency

25

penalty of the best case decreases to 9.75%. This study indicates that comprehensive heat integrations can

26

significantly improve the overall energy efficiency when the CFPP is integrated with PCC and

27

compression process.

28 29

Keywords: process simulation; heat integration; supercritical coal-fired power plant; post-combustion CO2 30 capture; CO2 compression. 31 32 1. Introduction 33

Greenhouse gases emissions have been on the increase since the start of industrial revolution. CO2 is the 34

main greenhouse gas accounting for over 60% of total greenhouse gas emissions [1]. The

35

Intergovernmental Panel on Climate Change (IPCC) indicates that CO2 emissions need to be cut by a 36

minimum of 50% to limit the average global temperature increment to 2°C in 2050 [2]. Carbon capture and

37

storage (CCS) is considered the key technology to mitigate CO2 emissions from fossil fuel-based power 38

generation.

39

A great portion of CO2 emissions is generated from the electricity and heat industry. Coal combustion is 40

estimated to be the largest source of electricity and heat generation, particularly in South Africa (93%),

41

Poland (92%), China (79%), India (69%), and United States (49%) [3, 4]. The majority of existing CFPPs

42

are based on subcritical steam cycles, however, supercritical CFPPs are rapidly spreading to replace

43

subcritical CFPPs, with advantages of higher thermal efficiency and lower CO2 emissions [5, 6]. The 44

average thermal efficiency of subcritical CFPPs is 35%, while supercritical CFPPs have about 5%pt higher

45

net efficiency [7]. Supercritical CFPPs would play an important role in global power generation and the

46

reduction of coal consumption.

47

Monoethanolamine (MEA)-based chemical absorption technology remains the first choice for CFPP due

48

to its high operational flexibility because it can be easily integrated into both the existing power plants and

49

new installations [8]. Moreover, this technology is characterized by a relatively high separation selectivity

50

[9-12], so that it is well-suited for treating low CO2 partial pressure flue gas from CFPP [13]. 51

Previous studies [14-16] indicates that there is a significant energy penalty when CFPP is couple with

52

PCC process, because of the steam extraction from CFPPs for solvent regeneration. This high energy

53

penalty constitutes the main barrier of the commercial deployment of CCS technology. There are two

54

solutions to reduce the energy penalty: (1) improving the performance of PCC process, or (2) retrofitting

55

the steam cycle of power plant with comprehensive heat integrations with PCC process.

56 57

The absorption process has been extensively researched to decrease its reboiler duty. Freguia and

58

Rochelle [17] performed sensitivity analyses on process variables to find operating conditions at low

59

energy requirement. Moullec et al. [18] and Babatunde et al. [19] evaluated various process modifications 60

through modelling and simulation. A variety of single solvents and blended solvents are studied and compared 61

to find advanced solvents possessing good performance and low price [20-22]. These processes are run in the 62

scale of pilot plant, however, another difficulty of commercial application of PCC technology in CFPP is to 63

evaluate the performance of PCC plants in industrial scale. Lawal et al. [16] scaled up the process according to 64

chemical engineering principles to match a specific CFPP. 65

Several other researchers focus on the thermal efficiency of CFPPs to improve the steam conditions in boiler. 66

Weitzel et al. [24] improved the overall CFPP thermal efficiency by 6% through adopting 700 ℃ technology in 67

steam generator instead of 600 ℃ technology. However, the steam conditions are related to the materials in

68

steam generator, critical steam piping and steam turbine. Thus this method is infeasible for retrofits of existing

69

CFPPs. One main strategy is recovering the waste heat of PCC plant to heat circulating water, which contributes

70

to a reduction of steam extraction for solvent regeneration. Hanak et al. [3] reduced the efficiency penalty by

71

0.43% through heat exchanger network (HEN) analysis. In the study of Gibbins and Crane [25], extracted steam

72

is desuperheated through exchanging heat with part of the reboiler condensate, and waste heat from CO2 capture 73

and compression process is recovered by heating circulating water, decreasing the efficiency penalty by 2.9%

74

for MEA and by 2.5% for KS-2. Besides, Lucquiaud and Gibbins [26] compared three capture ready steam

75

turbine options (clutched LP turbine, throttled LP turbine and Floating IP/LP crossover pressure), revealing that

76

the case with clutched LP turbine presented lowest efficiency penalty.

77

Based on above research, this paper focuses on the integration of steam cycle and PCC plant,

78

comprehensively considering heat exchanger network analysis, utilization of the superheat of extracted

steam, capture ready steam turbine options and steam-extraction locations. To do this, the steam cycle of a

80

600MWe supercritical CFPP was modelled and simulated, as well as the CO2 capture and compression 81

process. The CO2 capture process is scaled up to match the capacity of the 600MWe supercritical CFPP. 82

Furthermore, eight cases were simulated and compared regarding the energy efficiency improvement.

83

Two novelties can be claimed for this paper: 1) detailed study on scale-up of PCC process to match the

84

flue gas flowrate of a specific 600 MWe supercritical CFPP was performed. 2）comprehensive heat 85

integration options were studied for two different stream extraction from LP I (at 3.64 bar) and IP-LP

86

crossover (at 9.1 bar) respectively for solvent regeneration. Compared with previous studies such as Lawal

87

et al. (2012) [16], this study considered not only how to extract steam from steam turbine in power plant

88

for PCC reboiler, but also heat integrations between PCC, CO2 compressors and CFPP. More important is 89

that these possibilities have been combined in the case study.

90 91

2. Model development 92

2.1. Model development of Supercritical CFPP 93

94

Selected as the reference power plant was a 600 MWe supercritical CFPP (24.2 MPa/571℃/569℃) in 95

China (Figure1), in which approximately 1677.5t/h of high-pressure steam generated in the steam

96

generator passes through HP, IP, and LP turbines successively for electric power generation. In this power

97

plant, the exhausted steam is next condensed to water in the condenser at pressure of 0.0588bar, and

eight-98

stage steam (HP I & HP II; IP I & IP II; LP I, LP II, LP III & LP IV) is drawn off to heat the circulating

99

water (see Table 1). The first three-stage steam extraction is for HP feedwater heaters; the fourth-stage

100

steam extraction is for deaerator; and the last four-stage steam extraction is for LP condensate heaters. In

101

addition, fuel combustion produces a large amount of flue gas. Before entering the CO2 capture process, 102

flue gas is often treated with a series of chemical processes and scrubbers to remove particulate matter

103

and sulphur dioxide.

104

This supercritical CFPP is modelled in Aspen Plus® as base case to explore the influence of PCC

105

integration. The STEAMNBS property method is used to properly evaluate the steam process. All turbines

106

are simulated using Compr blocks set as isentropic turbines, and circulating water heaters are modelled as

107

HeatX blocks [23]. The boiler is replaced as a HeatX block to simplify the process. The overall

108

performance is shown in Table 2.

109 110

2.2. Model development and scale-up of PCC process 111

2.2.1. PCC process description 112

Figure 2 shows a typical CO2 chemical absorption process. CO2 from flue gas is chemically absorbed by 113

an MEA solution in the absorber column and then released from the top of the regenerator column with

114

high concentration. In this study, a closed-loop rate-based CO2 absorption model is developed in Aspen 115

Plus® and validated using the data from a pilot plant at University of Texas, Austin [27, 28]. All

116

parameters in the model and validation process are stated by Canepa, et al [23]. In the pilot plant, both the

absorber and regenerator column are 0.427m in diameter and packed with two sections of 3.05m packing.

118

The absorber is operated at atmospheric pressure with a random metal packing, IMTP no.40, while the

119

regenerator is operated at apressure of 1.7 bar and filled with a structured packing, Flexi Pac1Y.

120 121

2.2.2. Model scale-up 122

To match the capacity of a 600 MWe supercritical CFPP, the CO2 capture plant model has been scaled 123

up based on chemical engineering principles. As an initial input of Aspen Plus® model, a first-guess

124

diameter is required for the absorber and the regenerator. One engineering practice is to calculate the

125

column diameter from the maximum flooding vapour velocity which could be estimated by empirical

126

correlation equations and figures. In this study, a generalised pressure drop correlation figure (see Figure

127

11.46. in [29]) adapted from a figure by the Norton Co. was used. The abscissa and ordinate are presented

128

in Equation (1) and Equation (2) respectively [29].

129 130 * * w V LV w L

L

F

V

ρ

ρ

=

13.1(

)

(

/

)

(

)

V

F

K

µ

ρ

ρ

ρ

ρ

⋅

⋅

=

−

FLV is a flow parameter which is related to L/G ratio; K4 is a modified load which is evaluated from Figure 133

11.46. in [29] according to the value of FLV and assumed pressure drop. Fp is a packing factor. Based on 134

this, V*w (vapour mass flow rate per unit cross-sectional area) is calculated, then the total cross-sectional 135

area can be obtained given the flue gas flow rate. This methodology has also been applied in numerous

136

similar literatures [3, 16, 23].

137

Flooding and minimum liquid load are two primary limitations for the operating region of packed

138

columns. Flooding defines the upper operating line of packed column. The minimum liquid load is set to

139

ensure that the entire packing surface is wetted [16, 30]. In order to achieve good liquid and gas

140

distribution, pressure drop between 15 and 50 mmH2O per meter packing for absorber and regenerator 141

columns was recommended [29]. In this paper, pressure drop of 42 mmH2O per meter packing is selected 142

for the scale-up [3]. Here one important thing should be noticed that the design of the column internals

143

such as gas/liquid distributors and re-distributors is crucial to ensure good gas and liquid distribution inside

144

the absorber and regenerator in such large diameters.

145

The boundary conditions data can be seen in Table 3. A first-guess diameter of the absorber and

146

regenerator can be calculated using the above method. Starting from this, these parameters will be

147

improved in the development of the closed-loop CO2 absorption model in Aspen Plus ®

. In the simulation

148

of the closed-loop capture plant, lean loading (mol CO2/mol MEA) is an important parameter related to 149

reboiler duty. The change of reboiler duty at different lean loadings is presented in Figure 3; here it can be

150

seen that the reboiler duty first decreases as lean loading increases, and then it increases with the increase

151

of lean loading. Minimum reboiler duty is attained when lean loading is 0.23 mol CO2/mol MEA. 152

The relationship of different numbered columns and diameters is given in Figures 4 and 5. Considering

153

structural limitations, it is better to keep the column diameter less than 12.2m—thus, for the absorber, at

154

least three columns with diameters of 11.66m are needed [16, 31] whilst a two-column regenerator with a

155

diameter of 10.78m is selected. The overall performance of the capture plant with improved parameters is

156

shown in Tables 4 and 5.

157 158

2.3. Simulation of compression process 159

After the CO2 captured from the power plant, it will be pressurized at a pressure as high as 110 -150 bar 160

for pipeline transport and geologic sequestration [32, 33]. Thus a compression train is needed. In this study,

161

CO2 is pressurized to 90 bar by a four-stage compressor and then pressurized to 110bar by a pump. 162

Between two adjacent stages of the compressor, an intercooler cools the stream. A flash tank is set after the

163

intercooler of the first stage and second stage to draw off liquid water (Figure 6). In the simulation,

164

isentropic compression model is selected with 90% isentropic efficiency [18]. And the pressure drop of

165

intercoolers is assumed as 2% [34]. Simulation results are given in Table 6. There are four hot streams that

166

need to be cooled in the process, and the heat can be integrated into the steam cycle.

167 168

3. Integration of CFPP with PCC and compression process 169

170

A large amount of steam is drawn off from steam cycle to heat the reboiler because of the huge energy

171

required for solvent regeneration, as shown in Figure 7. In this way, all of the low-pressure condensate

172

heaters are removed, and a throttling valve (V1 in Figure 7) is added at the steam extraction location to

173

ensure the plant’s stability [35]. The solvent regeneration temperature in the reboiler of the capture plant is

174

120℃, meaning that hot steam used to heat the reboiler should be 130℃with 10℃ mean temperature

175

difference—that is to say that steam of 2.7 bar is required for solvent regeneration. However, the steam

176

extraction point is not casual; Table 1 details the eight stages of steam extraction in the steam cycle.

177

Consequently, the steam drawn off for solvent regeneration is usually decompressed to 2.7 bar by a

178

throttling valve V2 and cooled down to just above saturated temperature through transferring heat with

179

circulating water in H4. The power plant without PCC process has been simulated as the Base Case in

180

Section 2.2. In this section, this study focuses on the effect of PCC plant integration on power plant

181

performance.

182 183

3.1. Steam extraction from LP I (i.e. 3.64 bar) 184

3.1.1. Considerations 185

For the location selection of steam extraction for solvent regeneration, LP I (at 3.64 bar) is appropriate

186

because it is closest to 2.7 bar as seen in Table 1. After the steam is drawn from LP I, the steam is

187

decompressed to 2.7 bar and then cooled to its saturated state before entering the reboiler in PCC process.

188

In the steam cycle, thermal energy is needed to heat circulating water. In general, this energy is provided

189

by eight-stage steam extraction for a standalone CFPP. Once CFPP is integrated with CO2 capture and 190

compression process, energy saving could be achieved by coupling the hot streams of capture and

191

compression process with the steam cycle to heat circulating water. The properties of hot streams are

192

presented in Table 7. The stream named ‘CO2 cooling’ is from the last compressor and required to be 193

condensed to enter a pump. It should be noted that the heat load of the stream shown here does not involve

194

the heat of condensation because the condensation temperature is too low to be utilized. The highest

195

temperature of hot streams in Table 7 is 167℃ whilst circulating water is heated from 34℃ to 175.9℃ in

196

LP condensate heaters and then is heated from 175.9℃ to 272℃ in HP feedwater heaters. Therefore, only

197

circulating water in the low-temperature section can be heated by waste heat from CO2 capture and 198

compression process.

199 200

Moreover, a great amount of steam is drawn off for solvent regeneration; thus a throttling valve is

201

generally added to keep the stability, resulting in a throttling loss. On the other hand, there are usually

202

several sets of LP cylinders in the plant to avoid the turbine blade becoming too long when steam

203

expanding in power generation process. Consequently, if part of the LP turbine is taken out of service, the

204

rest LP turbine can work at conditions close to normal operating state; accordingly, the throttling loss is

205 avoided. 206 207 3.1.2. Case studies 208

For the scenario of steam extraction from LP I stream (3.64 bar) for solvent regeneration, three cases are

209

set up to study the effect of utilizing waste heat and taking part of the LP turbine out of service in below:

210

Case 1A: Basic integration of PCC into supercritical CFPP with steam extraction from LP I for PCC

211

reboiler.

212

Case 2A: Utilizing waste heat from the PCC and CO2 compression process for feedwater pre-heating in 213

CFPP & steam extraction from LP I in CFPP for PCC reboiler.

214

Case 3A: Taking part of LP cylinders out of service & Utilizing waste heat from the PCC and CO2 215

compression process for feedwater pre-heating in CFPP & steam extraction from LP I in CFPP for PCC

216

reboiler.

217

These three cases are set progressively, and the flow chart of case 3A is shown in Figure 8. In the

218

process of waste heat utilization, _∆T for heat transfer is set to 10℃. The circulating water is heated to 74℃

219

by the condenser of regenerator first, then it is divided into four parts and exchange heat with the four

220

intercoolers of compression process respectively, as a result, the four streams are heated to 138℃, 125℃,

221

131℃ and 157℃ respectively, and the average temperature is 139℃. So that the effect of PCC integration

222

can be investigated, the performance of the cases is presented as net power output, generating efficiency

223

and CO2 emissions, and compared with the base case described in section 2.2.Simulation results 224

comparison between these three cases and the base case are given in table 8. Generally introduction of the

225

CO2 capture process results in a large efficiency penalty in the supercritical CFPP. In Case 1A, the 226

efficiency penalty is 12.29% points and equals a decrease of 29.5% in the economic benefits of the power

227

plant. Waste heat is recovered in Case 2A, which makes an improvement of 0.54% points in generating

efficiency. This is because waste heat utilization decreases the flow rate of steam extraction for circulating

229

water heating. Furthermore, more than half of the LP steam is drawn off, and a throttling valve is added to

230

ensure the power plant stability. However, if half of the LP turbine is taken out of service, the other half

231

can still work in approximately normal condition; therefore, the throttling loss is avoided. The power plant

232

performance is shown in case 3A in which generating efficiency is improved by 0.9% after taking half of

233

the LP turbine out of service. Moreover, for new power plants, the capacity of every LP cylinder can be

234

designed according to the flow rate of steam extraction, which allows the corresponding LP cylinder to

235

shut down when integrating with PCC.

236 237

3.2. Steam extraction from IP-LP crossover (i.e. 9.1 bar) 238

3.2.1. Considerations 239

The overall performance of the power plant with steam extraction from LP I (i.e. 3.64 bar) was studied

240

in Section 3.1. Theoretically it is feasible to draw steam from any stage of steam turbine with pressure

241

higher than 2.7bar for solvent regeneration. However, it is not economical to draw steam when steam

242

pressure is too high considering the large throttling loss. As a typical case, we study steam extraction from

243

IP-LP crossover with steam pressure at 9.1 bar. The consideration of setting up Cases 1B, 2B and 3B is

244

similar to what has been analysed in Section 3.1.

245 246

3.2.2. Case studies 247

Three cases are developed to compare the performance of power plant with 9.1 bar steam extraction:

248

Case 1B: Basic integration of PCC into supercritical CFPP with steam extraction from IP-LP crossover

249

for PCC reboiler.

250

Case 2B: Utilizing waste heat from the PCC and CO2 compression process for feedwater pre-heating in 251

CFPP & steam extraction from IP-LP crossover in CFPP for PCC reboiler.

252

Case 3B: Taking part of LP cylinders out of service & Utilizing waste heat from the PCC and CO2 253

compression process for feedwater pre-heating in CFPP & steam extraction from IP-LP crossover in CFPP

254

for PCC reboiler.

255

In Case 2B and Case 3B, the temperature of the steam, which is freshly decompressed from 9.1 bar

256

steam, is too high to be cooled down to the saturated temperature by preheated circulating water. For such

257

a situation, part of the steam cooled down in the reboiler is returned back to mix with high-temperature

258

steam to effect the appropriate temperature, as shown in figure 9. In this way, less steam is drawn off and

259

more is used to generate electricity. Meanwhile, more condensate is produced from the condenser,

260

resulting in that waste heat from PCC plant is not able to improve the circulating water to the same

261

temperature in Case 3A. In the heat exchanger network, circulating water is heated to 74℃ first, then it is

262

divided into four streams which are heated to 133℃, 115℃, 127℃ and 152℃ respectively, the average

263

temperature is 133℃. The overall performance of these cases is presented in table 9.

264

From results (for steam extraction at IP-LP crossover) shown in Table 9, the net efficiency penalty in

265

Cases 1B, 2B and 3B are 14.9%, 14.04% and 13.0% respectively. However from results (for steam

extraction at LP I) shown in Table 8, the net efficiency penalty in Cases 1A, 2A and 3A are 12.29%, 11.75%

267

and 10.85% respectively. By comparison, steam extraction at lower pressure is more economical. This can

268

be explained theoretically that the throttling loss of decompressing higher pressure steam (9.1 bar) to 2.7

269

bar is more serious. On the other hand, the reduction of efficiency penalty from Case 1B to Case 3B (1.9%)

270

is lightly higher than it from Case 1A to Case 3A (1.44%). This is because the 9.1 bar steam saved in Case

271

3B due to heat integration is higher grade stream, resulting in a higher power output increment.

272 273

3.3. Auxiliary turbine 274

275

From Section 3.1 and Section 3.2, the net power output is improved through utilizing waste heat and

276

taking half of LP turbine out of service. However, the throttling valve V2 is still causing energy loss,

277

especially in Case 3B. In this section, the addition of an auxiliary turbine to decompress the steam

278

extracted from IP-LP crossover at 9.1 bar is considered. The throttling valve V2 is no longer necessary. As

279

this case is a further extension of Case 3B, this case is called Case 4B:

280

Case 4B: adding an auxiliary turbine (see Figure 10) to decompress the extraction steam & taking part of

281

LP cylinders out of service & utilizing waste heat from the PCC and CO2 compression process for 282

feedwater pre-heating in CFPP & steam extraction from IP-LP crossover in CFPP for PCC reboiler.

283

In Case 4B, the steam decompressed by the auxiliary turbine possesses less superheat to heat circulating

284

water and reboiler condensate. Thus more 9.1 bar steam than that in Case 3B is extracted to match the

285

reboiler duty, resulting in less condensate from condenser. In this way, circulating water from condenser is

286

able to be heated to higher temperature than that in Case 4B through waste heat recovery. Specifically, the

287

circulating water from condenser is heated to 74℃ first, then it is divided into four streams which are

288

heated to 138℃, 125℃, 131℃ and 157℃ respectively. The average temperature is 139℃. The

289

performance can be seen in Table 10. The net efficiency penalty in Case 4B is 9.75%, this result

290

demonstrates a substantial improvement of a 4% increment compared with Case 3B. Thus it can be seen

291

that the throttling loss in Case 3B is huge. The net efficiency penalty in this case is 9.75%, 1.1% points less

292

than it in Case 3A. Among all cases presented, Case 4B represents the best performance.

293 294

4. Conclusions 295

296

In this study, a steady state model for 600 MWe supercritical CFPP was developed, and seven cases were 297

studied to investigate the effect of integration with PCC process and CO2 compression process. Generating 298

efficiency for the reference case is 41.6%. It reduced to 29.31% when more than half of the steam was

299

extracted from LP I (at 3.64 bar) for solvent regeneration. Two methods, utilization of waste heat from

300

PCC process and CO2 compression process and taking half of LP turbine out of service, were adopted to 301

decrease the efficiency penalty, which improved the generating efficiency to 30.75%. Similar study was

302

performed in the cases of extracting steam from IP-LP crossover at 9.1 bar. The generating efficiency

303

reduced to 26.7% in the basic integration, and improved to 28.6% through adopting the two methods.

304

Extracting steam from IP-LP crossover at 9.1 bar caused more serious efficiency penalty due to the higher

throttling loss. However, an auxiliary turbine was added to decompress the 9.1 bar steam, which

306

contributed to a reduction of 3.25% in efficiency penalty. In this way, net generating efficiency is 31.85%

307

and the efficiency penalty is reduced to 9.75%. According to the results, comprehensive heat integration

308

modifications can effectively reduce the energy penalty when the CFPP is integrated with PCC and CO2

309 compression process. 310 311

Acknowledgement

The authors would like to acknowledge the financial support from the National Natural Science

314

Foundation of China (key project No. 51134017), EU FP7 Marie Curie International Research Staff

315

Exchange Scheme (Ref: PIRSES-GA-2013-612230) and State Key Laboratory of Chemical Engineering of

316 China (SKL-ChE-12Z01). 317 318

References

[1] IPCC. Climate change 2014: mitigation of climate change: contribution of working group III to the fifth 320

assessment report of the intergovernmental panel on climate change. Cambridge, United Kingdom and 321

New York, NY, USA: Cambridge University Press; 2014. 322

[2] IPCC. Managing the risks of extreme events and disasters to advance climate change adaptation. 323

Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press; 2012. 324

[3] Hanak DP, Biliyok C, Yeung H, Białecki R. Heat integration and exergy analysis for a supercritical high-ash 325

coal-fired power plant integrated with a post-combustion carbon capture process. Fuel 2014; 134: 126-326

139. 327

[4] IEA. Energy technology perspectives 2010: scenarios & strategies to 2050. Paris, France: IEA Publications; 328

2010. 329

[5] IEA. Technology roadmap: carbon capture and storage. Paris, France: IEA Publications; 2013. 330

[6] IEA. Tracking clean energy progress 2013: IEA input to the clean energy ministerial. Paris. France: IEA 331

Publications; 2013. 332

[7] Goto K, Yogo K, Higashii T. A review of efficiency penalty in a coal-fired power plant with post-combustion 333

CO2 capture. Applied Energy 2013; 111: 710-720. 334

[8] Wang M, Lawal A, Stephenson P, et al. Post-combustion CO2 capture with chemical absorption: A state-of-335

the-art review. Chemical Engineering Research and Design 2011; 89:1609-1624. 336

[9] Alie C, Backham L, Croiset E, Douglas PL. Simulation of CO2 capture using MEA scrubbing: a flowsheet 337

decomposition method. Energy Conversion and Management 2005; 46: 475-487. 338

[10] Kanniche M, Gros-Bonnivard R, Jaud P, et al. Pre-combustion, post-combustion and oxy-combustion in 339

thermal power plant for CO2 capture. Applied Thermal Engineering 2010; 30: 53-62. 340

[11] Rao AB, Rubin ES. A technical, economic, and environmental assessment of amine-based CO2 capture 341

technology for power plant greenhouse gas control. Environmental science & technology 2002; 36: 4467-342

4475. 343

[12] Singh d, Croiset E, Douglas PL, Douglas MA. Techno-economic study of CO2 capture from an existing coal-344

fired power plant: MEA scrubbing vs. O2/CO2 recycle combustion. Energy Conversion and Management 345

2003; 44: 3073-3091. 346

[13] Lawal A, Wang M, Stephenson P, Yeung H. Dynamic modelling of CO2 absorption for post combustion 347

capture in coal-fired power plants. Fuel 2009; 88: 2455-2462. 348

[14] Abu-Zahra MRM, Schneiders LHJ, Niederer JPM, et al. CO2 capture from power plants: Part I. A parametric 349

study of the technical performance based on monoethanolamine. International Journal of Greenhouse 350

Gas Control 2007; 1: 37-46. 351

[15] Davison J. Performance and costs of power plants with capture and storage of CO2. Energy 2007; 32: 352

1163-1176. 353

[16] Lawal A, Wang M, Stephenson P, Obi O. Demonstrating full-scale post-combustion CO2 capture for coal-354

fired power plants through dynamic modelling and simulation. Fuel 2012; 101: 115-128. 355

[17] Freguia S, Rochelle GT. Modeling of CO2 capture by aqueous monoethanolamine. AIChE Journal 2003; 49: 356

1676-1686. 357

[18] Moullec YL, Kanniche M. Screening of flowsheet modifications for an efficient monoethanolamine (MEA) 358

based post-combustion CO2 capture. International Journal of Greenhouse Gas Control 2011; 5: 727-740. 359

[19] Oyenekan B A, Rochelle G T. Alternative stripper configurations for CO2 capture by aqueous amines. AIChE 360

Journal 2007, 53(12): 3144-3154. 361

[20] Freeman S A, Dugas R, Van Wagener D H, Nguyen T, Rochelle G T. Carbon dioxide capture with 362

concentrated, aqueous piperazine. Int J Greenhouse Gas Control 2010; 4: 119–124 363

[21] Aroonwilas A, Veawab A. Integration of CO2 capture unit using single- and blended-amines into 364

supercritical coal-fired power plants: implications for emission and energy management. Int J Greenhouse 365

Gas Control 2007; 1: 143–150. 366

[22] Conway W, Bruggink S, Beyad Y, et al. CO2 absorption into aqueous amine blended solutions containing 367

monoethanolamine (MEA), N, N-dimethylethanolamine (DMEA), N, N-diethylethanolamine (DEEA) and 2-368

amino-2-methyl-1-propanol (AMP) for post combustion capture processes. Chemical Engineering Science 369

2014; 126: 446-454. 370

[23] Canepa R, Wang M, Biliyok C, Satta A. Thermodynamic analysis of combined cycle gas turbine power plant 371

with post-combustion CO2 capture and exhaust gas recirculation. Proceedings of the Institution of 372

Mechanical Engineers 2013; 227: 89-105. 373

[24] Weitzel P S, Tanzosh J M, Boring B, et al. Advanced Ultra-Supercritical Power Plant (700 to 760C) Design 374

for Indian Coal. Power-Gen Asia 2012, Bangkok, Thailand. 375

[25] Gibbins J R, Crane R I. Scope for reductions in the cost of CO₂ capture using flue gas scrubbing with amine 376

solvents. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 377

2004; 218(4): 231-239. 378

[26] Lucquiaud M, Gibbins J. Retrofitting CO2 capture ready fossil plants with post-combustion capture. Part 1: 379

requirements for supercritical pulverized coal plants using solvent-based flue gas scrubbing. Proceedings 380

of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 2009; 223(3): 213-226. 381

[27] Dugas RE. Pilot plant study of carbon dioxide capture by aqueous monoethanolamine (MSc Thesis), The 382

University of Texas, Austin, USA, 2006. 383

[28] Zhang Y, Chen H, Chen C C, et al. Rate-based process modeling study of CO2 capture with aqueous 384

monoethanolamine solution. Industrial & engineering chemistry research 2009; 48(20): 9233-9246. 385

[29] Towler G, Sinnott RK. Chemical engineering design: principles, practice, and economics of plant and 386

process design. 2nd ed. Oxford, UK: Elsevier; 2013. 387

[30] Stichlmair FJ, Johann G. Distillation: principles and practices. New York, USA: Wiley-VCH; 1998. 388

[31] Ramezan M, Skone T, Nsakala N, et al. Carbon dioxide capture from existing coal-fired power plants. 389

DOE/NETL-401/110907; NETL: Pittsburgh, PA: 2007. 390

[32] Luo X, Mistry K, Okezue C, Wang M, et al. Process Simulation and Analysis for CO2 Transport Pipeline 391

Design and Operation - Case Study for the Humber Region in the UK. Computer Aided Chemical 392

Engineering 2014; 1633-1638. 393

[33] Luo X, Wang M, Oko E, Okezue C. Simulation-based techno-economic evaluation for optimal design of CO2 394

transport pipeline network. Applied Energy 2014; 132: 610-620. 395

[34] Witkowski A, Rusin A, Majkut M, Rulik S, Stolecka K. Comprehensive analysis of pipeline transportation 396

systems for CO2 sequestration. Thermodynamics and safety problems. Energy Convers Manage 2013; 76: 397

665–673. 398

[35] Xu G, Yang Y, Ding J, et al. Analysis and optimization of CO₂ capture in an existing coal-fired power plant in 399

China. Energy 2013; 58: 117-127. 400

Table 1. Eight-stage steam extraction

Extraction-stage HP I HP II IP I IP II LP I LP II LP III LP IV Extraction pressure (bar) 61.54 41.48 18.52 9.1 3.64 1.11 0.546 0.175

Table 2. Overall performance of the supercritical CFPP without CO2 capture process

Gross power output（MWe） 603.0

Power consumption（MWe） 15.5

Net power output（MWe） 587.5

Fuel input（MWth） 1414

Generating efficiency（%LHV net） 41.6

Flow rate of flue gas（kg/s） 707.8

CO2 concentration in flue gas ( wt% ) 19.54

Table 3. Boundary conditions of PCC process

Flue gas flowrate (kg/s) 707.8

Flue gas CO2 content (Mole %) 13.09

Flue gas temperature (℃) 44

Solvent MEA content (wt%) 30

Lean solvent flowrate (t/h) 6000 Lean loading (mol CO2/mol MEA) 0.23

Capture level 90%

Table 4. Absorber and regenerator design

Absorber Regenerator

Pressure drop (mm water/m) 42 42

Column diameter (m) 11.66 10.78

Column number 3 2

Column packing IMTP no.40 Flexi Pac1Y

Packing height (m) 30 30

Table 5. Overall performance of capture plant

Lean solvent flowrate (t/h) 6995

L/G ratio (mass basis) 2.75

Lean loading (mol CO2/ mol MEA) 0.23 Rich loading (mol CO2/ mol MEA) 0.54 Lean Solvent MEA content (wt%) 30.04

CO2 stream purity (wt%) 94.98

Condenser duty (MWth) 40.79

Reboiler duty (MWth) 572

Table 6. Performance of CO2 compression process.

Inlet pressure(bar) 1.7

Outlet pressure (bar) 110

Power consumption(MWe) 37.8

CO2 compression work(kWh/tCO2) 84.8

Table 7. Property of hot streams Stream Stream type Inlet temperature (℃℃℃℃) Outlet temperature (℃℃℃℃) Heat load (MWth)

Condenser in Regenerator Hot 84 59 40.79

CO2 intercooling 1 Hot 148 51 25.37

CO2 intercooling 2 Hot 135 54 11.67

CO2 intercooling 3 Hot 141 73 8.98

Table 8. Thermal performance of Cases with 3.64 bar steam extraction.

Case Base case Case 1A Case 2A Case3A

Gross power output（（（（MWe）））） 603.0 468.08 475.7 488.35

Pumping work （（（（MWe）））） 15.4 15.8 15.8 15.8

Compression work（（（（MWe）））） -- 37.8 37.8 37.8

Total energy consumption（（（（MWe）））） 15.4 53.6 53.6 53.6 Net power output（（（（MWe）））） 587.6 414.48 422.1 434.75

Fuel input（（（（MWth）））） 1414 1414 1414 1414

Generating efficiency（（（（%）））） 41.6 29.31 29.85 30.75

Net energy penalty（（（（%）））） -- 29.46 28.17 26.01

Net efficiency penalty（（（（%）））） -- 12.29 11.75 10.85 CO2 emissions（（（（g/kWh）））） 847.3 120.12 117.95 114.52 CO2 emission reduction（（（（g/kWh）））） -- 727.18 729.35 732.78

Table 9. Thermal performance of Cases with steam extraction from IP-LP crossover at 9.1 bar

Case Base case Case 1B Case 2B Case 3B

Gross power output（（（（MWe）））） 603.0 431.15 443.25 458.03

Pumping work （（（（MWe）））） 15.4 15.8 15.8 15.8

Compression work（（（（MWe）））） -- 37.8 37.8 37.8

Total energy consumption（（（（MWe）））） 15.4 53.6 53.6 53.6 Net power output（（（（MWe）））） 587.6 377.55 389.65 404.43

Fuel input（（（（MWth）））） 1414 1414 1414 1414

Generating efficiency（（（（%）））） 41.6 26.7 27.56 28.60

Net energy penalty (%) -- 35.75 33.69 31.25

Net efficiency penalty（（（（%）））） -- 14.9 14.04 13.0 CO2 emissions（（（（g/kWh）））） 847.3 131.87 127.77 123.10 CO2 emission reduction（（（（g/kWh）））） -- 715.43 719.53 724.20

Table 10. The performance of Case 4B with an auxiliary turbine

Case Base case Case 4B

Gross power output（（（（MWe）））） 603.0 503.98 Pumping work （（（（MWe）））） 15.4 15.8 Compression work（（（（MWe）））） -- 37.8 Total energy consumption（（（（MWe）））） 15.4 53.6 Net power output（（（（MWe）））） 587.6 450.38

Fuel input（（（（MWth）））） 1414 1414 Generating efficiency（（（（%）））） 41.6 31.85

Net energy penalty (%) -- 23.35

Net efficiency penalty（（（（%）））） -- 9.75 CO2 emissions（（（（g/kWh）））） 847.3 110.55 CO2 emission reduction（（（（g/kWh）））） -- 736.75

Figure 4. Absorber diameter as function of the number of columns Figure 4. Absorber diameter as function of the number of columns Figure 4. Absorber diameter as function of the number of columns

Figure 5. Regenerator diameter as function of the number of columns Figure 5. Regenerator diameter as function of the number of columns Figure 5. Regenerator diameter as function of the number of columns

Figure

Figure 10. Flow diagram of